640 front end assembly question

Okay, on re assmbly I noticed a small hole in the top of the upper neck bearing cover, that coincides with a similar hole on the underside of the upper tree. Is there some sort of dowel pin that holds the two together so the bearing cup rotates with the upper tree? Stands to reason, but there isn't one, and don't see one in any exploded front end views.

You're correct. Positively locates top tree to upper bearing cone, so they turn together. It's a little steel dowel pin. About 1/8 - 3/16 dia, can't remember exactly, sticks out about the same. HTH, Neil

Thanks for the reply.

I couldn't find it in Greer's exploded view so I sifted through collection of unloved drill bits & when I
found one that fit cut 5/8 off the top.